The following U.S. and PCT Patent Publications are believed to represent the current state of the art: U.S. Pat. Nos. 7,099,553; 6,972,401; 5,257,340; 6,783,269; 5,905,583; 5,295,047; 7,163,326; 6,648,496 and 7,021,809; U.S. Patent Application Publication Nos. 2005/0248540 and 2005/0128190; and PCT Application No. WO 2009/029764 A1